The subject application pertains to the art of video inspection, and more particularly to improved illumination therefor implementing a highly integrated isotropic illumination emitter.
The invention is particularly applicable to providing improved, isotropic illumination for inspection of translucent or partially translucent materials or objects and will be described with particular reference thereto. However, it will also be appreciated that the invention has broader application, such as in providing illumination for any application in which isotropic light is advantageous.
Video inspection has become a well accepted and advantageous means of assuring quality control of manufactured product. Systems employing such inspection are particularly useful in connection with mass-produced items such as containers, including bottles, cans, and the like.
Early inspection system relied mainly on sophisticated, computation-intensive algorithms to accomplish inspection. In U.S. Pat. No. 4,882,498 owned by Pressco Technology, Inc., assignee hereof, the contents of which are incorporated herein by reference, an early understanding that significant improvements would be achieved by engineering lighting was provided. Manipulation and refinement of lighting techniques provides a cleaner, truer image from which the video inspection process may be commenced. This serves to minimize computation and algorithm complexity while simultaneously improving inspection throughput and integrity. The above-noted patent utilized solid-state light emitting diode illumination for its light generation. This invention acknowledged and facilitated improvements by providing easy manipulatable, highly-homogeneous lighting. While the resultant inspection improvement was marked, certain applications for video inspection would be even better realized with the provision of a more uniform, isotropic lighting. This is particularly true in connection with inspection of light transmissive or translucent specimens.
The present invention contemplates a new and improved illumination system particularly suited for video inspection which overcomes many of the above-referred problems, and others, and provides an isotropic illumination source which is simple, economical, and facilitates high integrity inspection. The present system teaches an improved, isotropic illumination source that defeats most prevalent total internal reflection effects associated with refraction shadowing in a transparent medium.